diff --git a/include/bitcoin/system/chain/chain_state.hpp b/include/bitcoin/system/chain/chain_state.hpp
index fb8823a5b6..eeda1cc973 100644
--- a/include/bitcoin/system/chain/chain_state.hpp
+++ b/include/bitcoin/system/chain/chain_state.hpp
@@ -19,8 +19,8 @@
 #ifndef LIBBITCOIN_SYSTEM_CHAIN_CHAIN_STATE_HPP
 #define LIBBITCOIN_SYSTEM_CHAIN_CHAIN_STATE_HPP
 
-#include <memory>
 #include <deque>
+#include <memory>
 #include <bitcoin/system/chain/checkpoint.hpp>
 #include <bitcoin/system/chain/context.hpp>
 #include <bitcoin/system/chain/enums/flags.hpp>